The present disclosure relates to an image forming apparatus including a processing unit to which a drum unit having a photosensitive drum is detachably attached.
Some of an image forming apparatus, such as a copying machine and a printer, have a configuration in which a processing unit is detachably attached to an apparatus main body. Into the processing unit, a drum unit, a development unit and an intermediate transferring unit are integrated. The drum unit supports a photosensitive drum so as to be rotatable. The development unit supports a development device. The intermediate transferring unit supports an intermediate transferring belt so as to be rotatable.
The processing unit of an example of the image forming apparatus is configured such that the drum unit, the development unit and the intermediate transferring unit are positioned and supported between two coupling members. Each unit has positioning projections while the two coupling members has positioning holes with which the positioning projections are engaged. By these positioning projections and positioning holes, these units are positioned relatively to each other.
However, the above image forming apparatus requires a disassembling work of the processing unit at maintenance and replacement of each unit. This lowers workability.
The processing unit of another example of the image forming apparatus is configured such that the drum unit and the development unit are detachably supported to a square cylindrical shaped process frame. The image forming apparatus is provided with a lock member which supports each of both ends of a rotating shaft of the photosensitive drum. The lock member is configured to be engaged with the process frame.
In the above configuration, if a gap between the photosensitive drum and the process frame in a direction of the rotating shaft becomes narrow as the image forming apparatus is reduced in size, a length of a portion where the lock member and the process frame are engaged with each other becomes small. Then, the lock member may be easily detached from the process frame, and therefore it becomes difficult to position the drum unit stably.